Non-dispersive process for oil recovery

ABSTRACT

A method of recovering one or more insoluble oils from a liquid source using one or more membrane or membrane contactors, comprising the steps of: pumping the liquid source comprising the one or more oils to the membranes or membrane contactors, contacting the liquid source with a first surface of the membrane or membrane contactors, coalescing the one or more oils within the liquid source onto the first surface of the membrane contactors, pumping one or more recovery fluids through the membrane or membrane contactors in contact with the second surface of the membrane or membrane contactors, and removing a first stream of oil coalesced from the second surface of the membranes or membrane contactors.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a continuation-in-part ofU.S. patent application Ser. No. 13/006,342 filed Jan. 13, 2011, whichclaims priority to U.S. Provisional Application Ser. No. 61/295,607,filed Jan. 15, 2010; and is related to and claims priority to:Continuation-in-Part applications U.S. Ser. No. 13/280,028 filed Oct.24, 2011 and U.S. Ser. No. 13/358,897, filed Jan. 26, 2012; and furtherclaims priority to: U.S. Ser. No. 61/659,918, filed Jun. 14, 2012 andU.S. Ser. No. 61/769,286, filed Feb. 26, 2013, the entire contents ofall of which are incorporated herein by reference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates in general to the field of insoluble oilrecovery from liquid sources, and more particularly, to a microporousmembrane based method for recovering oil.

STATEMENT OF FEDERALLY FUNDED RESEARCH

None.

REFERENCE TO A SEQUENCE LISTING

None.

BACKGROUND OF THE INVENTION

Without limiting the scope of the invention, its background is describedin connection with recovery methods for insoluble and low solubilitycompounds having economic value from aqueous mixtures that may includeone or more types of biological cells or cellular debris.

U.S. Pat. No. 3,956,112, issued to Lee, et al., is directed to amembrane solvent extraction. Briefly, this patent is said to describe amembrane solvent extraction system that is used to separate twosubstantially immiscible liquids and extract a solute through a solventswollen membrane from one solvent liquid phase to the extracting solventliquid without direct contact between the liquid phases. The membraneextraction method has advantages over conventional solvent extractionand may be applied as the mechanism in separation, purification,pollutant removal and recovery processes. This reference relies onliquid extraction, as the solvent swells the membrane to provide theseparation.

U.S. Pat. No. 4,439,629 issued to Ruegg (1984) describes a process forextracting either or both beta-carotene or glycerine from algaecontaining these substances, especially from algae of the generaDunaliella. According to the Ruegg patent either or both ofbeta-carotene or glycerine can be extracted from algae. If it is desiredto extract beta-carotene, the algae are first treated with calciumhydroxide and then filtered. The residue from this filtration is treatedwith a beta-carotene solvent, which removes the beta-carotene from theresidue and into the solvent. The beta-carotene can be recovered fromthe solvent by conventional means. If it is desired to extractglycerine, the filtrate from the treatment of the algae with calciumhydroxide is neutralized, concentrated and the residue from the solid istreated with a lower alkanol to remove glycerine from the residue.

U.S. Pat. No. 5,252,220, issued to Coughlin, et al., is directed to thepreparation of analytical samples by liquid-liquid extraction usingmicroporous hollow-fiber membranes. Briefly, this patent is said toteach a method and apparatus for accomplishing improved liquid-liquidextraction employing microporous hollow-fiber membranes. A number ofpossible modes of liquid-liquid extraction are possible according to theinvention. As with the prior art, this patent relies on the interactionbetween two liquids, one of the contact side and one on the other sideof the membrane for separation.

U.S. Pat. No. 5,378,639 issued to Rose et al. (1995) discloses a methodfor the solvent-extraction of β-carotene from an aqueous algal biomasssuspension, whereby a vegetable oil which is immiscible with water ismixed with an aqueous biomass suspension, the biomass containing theβ-carotene, to form a mixture of the organic phase and the aqueoussuspension, whereby the β-carotene is caused to dissolve in the organicphase. This is followed by separation of the organic phase from theaqueous phase by passing the organic phase containing the dissolvedβ-carotene through a semi-permeable membrane to effect microfiltrationor ultrafiltration of the organic phase. The membrane is of a materialthat is hydrophobic and the organic phase is passed through the membranewith a pressure drop across the membrane which is lower than that whichcauses the aqueous phase to pass through the membrane.

Finally, U.S. Pat. No. 6,436,290, issued to Glassford is directed to amethod and apparatus for separating mixtures of organic and aqueousliquid phases. Briefly, this patent is said to include a method andapparatus for separating a mixture containing an aqueous liquid and animmiscible organic phase using microporous hollow fibers. Such mixturesare separated into a substantially organic-free aqueous phase and asubstantially aqueous-free organic phase. The mixture is pressurized ina controlled low shear manner to minimize emulsification as it iscontacted with the fibers. Productivity is said to be enhanced byseparating as a third product stream, a further organic phase containingonly small amounts of an aqueous phase, which for some applications canusefully be combined with the substantially aqueous-free organic phase.

SUMMARY OF THE INVENTION

The present invention describes additional methods for coalescinginsoluble oil from mixtures using a hydrophobic microporous hollow fibermembrane. In one embodiment, the present invention does not recover adissolved solute from a carrier using another immiscible liquid calledthe solvent, but rather, relies on recovering insoluble oil from anoil/water based mixture by coalescence and not extraction. These novelprocesses could be used in a wide variety of commercially significantapplications such as: (i) recovery of released or secreted algal oilfrom an aqueous mixture, (ii) recovery and removal of insolublehydrocarbon and hydrocarbon-rich molecules from aqueous mixtures, (iii)recovery of Omega fatty acids from an aqueous mixture, (iv) recovery ofBeta-carotene from an aqueous mixture, (v) removal of oil from producedwater in petroleum exploration and production and (vi) exclusion ofwater or other lipophobic liquids from an oil-rich liquid stream.

The novel separation process of the present invention utilizes anon-dispersive method to coalesce and recover an insoluble oil from aliquid source, aqueous slurry, or liquid mixture. As an example, therecovery of non-polar algal oil from an algal concentrate is described.The technique utilizes a microporous hollow fiber membrane contactor.The inventors have tested the Liqui-Cel Extra Flow Contactor,commercially used for gas/liquid contacting, to obtain >80% recoveryefficiency and process concentrates up to 10% bio-cellular solidswithout membrane fouling. The novel technique of the present inventionutilizes the large coalescing area provided by the surface of themicroporous hollow fibers when filled with a hydrophobic recovery fluidand minimizes the actual contact of the hydrophobic fluid with the(e.g., algae) biomass and aqueous phase.

The novel separation process described herein can be coupled with avariety of appropriate recovery fluids for recovery of insolublecompounds, depending upon the types of compound or compounds to berecovered. The choice of recovery fluid will impact both the sub-set ofcompounds recovered from the liquid source as well as the downstreamsteps needed to economically and efficiently use compounds from therecovery fluid. Differential recovery of desired molecules, for example,recovery of non-polar oils, but not more polar oils, can be achieved bychoice of recovery fluid. Segregation of non-polar oils from polar oils,specifically polar oils containing phosphorous (e.g., phospholipids), ishighly advantageous as phosphorus containing compounds complicate boththe refining and transesterification processes used to createtransportation fuels and petrochemical feedstocks.

In one embodiment the present invention discloses a method of separatingoil/water mixtures, or liquid source, using hydrophobic microporoushollow fiber membrane modules comprising a plurality of microporoushollow fiber membranes comprising the steps of: (i) pumping theoil/water mixture through the inlet port of the contactor to ashell-side of the contactor, (ii) pumping one or more recovery fluidsthrough a second inlet port of the contactor to the one or more hollowfiber membranes on a fiber side of the contactor; wherein the one ormore recovery fluids counterflows with the liquid source on theshell-side of the contactor. The one or more recovery fluids compriseone or more hydrophobic liquids, a diesel or biodiesel, an algal oil, ahydrocarbon or non-polar oil or mixtures thereof, (iii) contacting theliquid source on the shell-side with the recovery fluid on the tubesurface, (iv) removing a first stream from a first outlet port in thecontactor, wherein the first stream comprises an oil/water mixture, and(v) removing a second stream from a second outlet port in the contactor,wherein the second stream comprises the recovery fluid and the one ormore coalesced oils. The method described in the embodiment of thepresent invention further comprises the steps of: (i) collecting the oneor more coalesced oils in a recovery vessel, (ii) recycling the recoveryfluid by pumping through the one or more microporous hollow fibermembranes to process additional volumes of oil/water mixture, and (iii)pumping the oil/water mixture to another contactor to remove additionaloil.

In another aspect the counterflowing recovery fluid compriseshydrophobic liquids, alkanes such as hexane, and aromatic solvents suchas benzene, toluene, and ethers such as diethyl ether, halogenatedsolvents such as chloroform, dichloromethane, and esters such as ethylacetate. In yet another aspect 45-100% of the one or more oils in theoil/water mixture are coalesced by the method of the present invention.As per the method described in the present invention 45%, 55%, 60%, 65%,70%, 75%, 80%, 85%, 90%, 95%, and 100% of the one or more oils in theoil/water mixture are recovered.

Another embodiment of the present invention discloses a method ofrecovering one or more insoluble oils from a liquid source using one ormore hydrophobic membranes or membrane modules comprising the steps of:(i) feeding the liquid source comprising the one or more insoluble oilsby pumping in a contactor or a vessel, (ii) pumping one or more recoveryfluids through the one or more membranes or membrane modules, whereinthe one or more recovery fluids counterflows with the liquid source inthe contactor or the vessel, wherein the one or more recovery fluidscomprise one or more hydrophobic liquids, a biodiesel, an algal oil, anon-polar oil or mixtures and combinations thereof, (iii) contacting theone or more insoluble oils in the liquid source in the contactor or thevessel with one or more recovery fluids pumped through the one or moremembranes or membrane modules, (iv) removing a first stream from thecontactor or the vessel, wherein the first stream comprises the liquidsource without the one or more insoluble oils, and (v) removing a secondstream from the contactor or the vessel, wherein the second streamcomprises the one or more recovery fluids and the one or more recoveredinsoluble oils.

In one embodiment, the present invention includes a method of recoveringone or more insoluble oils from a liquid source using one or moremembrane or membrane contactors, comprising the steps of: pumping theliquid source comprising the one or more oils to one or more membranesor membrane contactors, wherein the liquid source does not contain anamount of solvent sufficient to disperse the oils; contacting the liquidsource with a first surface of the one or more membrane or membranecontactors; coalescing the one or more oils within the liquid sourceonto the first surface of the one or more membrane contactors; pumpingone or more recovery fluids through the one or more membrane or membranecontactors in contact with the second surface of the one or moremembrane or membrane contactors; and removing a first stream of oilcoalesced from the second surface of the one or more membranes ormembrane contactors. In one aspect, the method further comprises thesteps of collecting the one or more coalesced oils in a collectionvessel; and exposing the liquid source one or more times to the one ormore membranes or membrane contactors by pumping through the one or moremembranes or membrane contactors to process the liquid source two ormore times to recover additional oil by coalescence. In another aspect,the liquid source is selected from at least one of oily water, oilindustry waste streams, oil contaminated water or brine, wastewater, oilcontaining drainage water, water contaminated with oil, seawatercontaminated with oil, brine contaminated with oil, industrial effluentsthat comprise oil, natural effluents that comprise oil, drilling mud,tailing ponds, leach residue, produced water, oil sands tailing, fracwater, connate water, an oil/water/solid mixture, a gravity separatedoil/water/solid mixture, water-oil mixtures, aqueous slurries, aqueousslurries comprising broken cells, live cells or organisms, biocellularmixtures, lysed cellular preparations, or lipophobic contaminants. Inanother aspect, the liquid source is more than 90% water and the processis used to purify the water by removing the oil. In another aspect, theliquid source is an industrial liquid stream, oil contaminated water orbrine, drilling mud, produced water and oil sands tailings the aqueousmixture is processed by the method within 1, 2, 4, 6, 8, 12, 24, 26, 48or 72 hours from production. In another aspect, the one or moremembranes or membrane contactors comprise a hydrophobic hollow fibermembrane selected from at least one of polyethylene, polypropylene,polyolefins, polyvinyl chloride (PVC), amorphous Polyethyleneterephthalate (PET), polyolefin copolymers, poly(etheretherketone) typepolymers, surface modified polymers, or surface modified polymerscomprise polymers modified chemically at one or more halogen groups bycorona discharge or by ion embedding. In another aspect, 45%, 50%, 55%,60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, 99% and 100% of the one ormore oils in the liquid source are recovered.

In another embodiment, the present invention includes a method ofrecovering one or more insoluble oils from a liquid source using one ormore membranes or membrane contactors comprising the steps of:contacting a liquid source comprising oil with a first surface of theone or more membranes or membrane contactors, wherein the oil coalescesat the first surface of the one or more membranes or membrane contactorsand wherein the oils pass-through the one or more membranes or membranecontactors without liquid-to-liquid contact; and collecting an oilstream of coalesced oil from the second surface of the membrane ormembrane modules without the need for a recovery fluid. In anotherembodiment, the present invention includes a method for separating oilfrom lipophobic contaminants and solid contaminants in a contaminatedoil, comprising the steps of: contacting a source of contaminated oilwith a first surface of one or more membranes or membrane contactors;coalescing the one or more oils within the contaminated oil bycontacting the contaminated oil with a first surface of one or moremembrane contactors; separating the oil from lipophobic contaminantswith the one or more membranes or membrane contactors; and collectingthe oil coalesced thereby. In one aspect, the contaminated oil is atleast one of an oil-rich stream, crude oil, transportation fuel, heatingoil, refined petroleum products, petrochemicals, transformer oil, motoroil, lubricating oil, bio-oils, renewable oils, vegetable oils,reclaimed oils, waste oils, or oil sands tailings. In another aspect,the contaminated oil is not subjected to gravity separation prior toprocessing, is subjected to gravity separation prior to processing, isseparated by a centrifugal, centripedal, or hydrocyclone device orprocess. In another aspect, the contaminated oil is processed by the oneor more membranes or membrane contactors within 1, 2, 4, 6, 8, 12, 24,26, 48 or 72 hours from production. In another aspect, the one or moremembranes or membrane contactors are further defined as a hollow fibermicroporous hydrophobic membrane selected from at least one ofpolyethylene, polypropylene, polyolefins, polyvinyl chloride (PVC),amorphous Polyethylene terephthalate (PET), polyolefin copolymers,poly(etheretherketone) type polymers, surface modified polymers, orsurface modified polymers comprise polymers modified chemically at oneor more halogen groups by corona discharge or by ion embeddingtechniques. In another aspect, the oil separated from the water by theone or more membranes or membrane contactors is mixed with acounterflowing fluid on the second surface of the one or more membranesor membrane contactors, wherein the at least one counterflowing fluidselected from hydrophobic liquids, alkanes such as hexane, aromaticsolvents such as benzene, toluene, ethers such as diethyl ether,halogenated solvents such as chloroform, dichloromethane, ethyl acetate,and esters. In another aspect, the counterflowing hydrophobic liquid isoil recovered from a similar liquid source using the membrane contactorwithout a recovery fluid or by another method. In another aspect, thecontaminated oil is from a bioreactor.

Yet another embodiment of the present invention includes a method ofrecovering one or more oils from an aqueous mixture using one or moremembrane or membrane contactors, comprising the steps of: pumping theaqueous mixture comprising the one or more oils into contact with afirst surface of the one or more membrane or membrane contactors;coalescing the one or more oils from the aqueous mixture onto the firstsurface of the one or more membrane or membrane contactors; andcollecting a stream of coalesced oil from the second surface of the oneor more membranes or membrane contactors, wherein the stream comprisesthe oils without the need for a counterflowing recovery fluid. In oneaspect, the aqueous mixture is selected from at least one of oily water,oil industry waste streams, oil contaminated water or brine, wastewater,oil containing drainage water, water contaminated with oil, seawatercontaminated with oil, brine contaminated with oil, industrial effluentsthat comprise oil, natural effluents that comprise oil, drilling mud,tailing ponds, leach residue, produced water, oil sands tailing, fracwater, connate water, an oil/water/solid mixture, a gravity separatedoil/water/solid mixture, water-oil mixtures, aqueous slurries, aqueousslurries comprising broken cells, live cells or organisms, biocellularmixtures, lysed cellular preparations, or lipophobic contaminants thathave not been separated or have been separated by at least one ofgravity, centrifugal, centripedal, or hydrocyclone separation. Inanother aspect, the aqueous mixture is processed by the method within 1,2, 4, 6, 8, 12, 24, 26, 48 or 72 hours from production. In anotheraspect, the aqueous mixture contains one or more organisms that includeat least one of intact cells, lysed cells, apoptotic cells, necroticcells, wherein organisms comprises two or more different organisms,wherein organism is a yeast, algae or bacteria, or wherein the organismis capable of secreting oil or causing the accumulation of oil outsideliving cells. In another aspect, the aqueous mixture contains one ormore organisms that are genetically modified to render them capable ofsecreting hydrophobic components, organisms that are capable of causingaccumulation of the one or more hydrophobic components outside livingcells, organisms that are capable of causing accumulation of the one ormore hydrophobic components outside living cells upon induction with oneor more chemical probes, exogenous agents, or pharmaceuticals, orcombinations thereof. In another aspect, the method further comprisescontacting the organism with chemical probes, exogenous agents, orpharmaceuticals, whereby the metabolism of the one or more organism ismodified, wherein at least one organism causes accumulation of the oneor more oils outside living cells. In another aspect, the method furthercomprises the step of contacting the one or more oils in the liquidsource to remove oil, then returning the aqueous mixture to a growthenvironment. In another aspect, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%,85%, 90%, 95%, 98%, 99% or 100% of the one or more insoluble oils in theliquid source are recovered. In another aspect, the source of theaqueous mixture is a growth environment for algae, bacteria or yeast andthe insoluble oils are recovered the using one or more membrane ormembrane contactors comprising the steps of: contacting the growth mediacomprising organisms and insoluble oils with a first surface in the oneor more membrane or membrane contactors; removing a first stream fromthe contactor or the vessel, wherein the first stream comprises thegrowth media and organisms, wherein the organisms can continue toproduce the insoluble oils; and removing a second stream from the secondsurface of one or more membrane or membrane contactors, wherein thesecond stream comprises the one or more insoluble oils without the needfor a recovery fluid. In another aspect, the method further comprisesfeeding or pumping the first stream to the growth environment to resumeoil production by the organisms. In another aspect, the one or moremembrane or membrane contactors are selected from at least one ofpolyethylene, polypropylene, polyolefins, polyvinyl chloride (PVC),amorphous Polyethylene terephthalate (PET), polyolefin copolymers,poly(etheretherketone) type polymers, surface modified polymers, orsurface modified polymers comprise polymers modified chemically at oneor more halogen groups by corona discharge or by ion embeddingtechniques.

Another embodiment of the present invention includes a system forrecovering one or more oils from an aqueous mixture comprising using oneor more non-dispersive membrane or membrane contactors, comprising: asource of a stream comprising an aqueous mixture containing oil; a pumpthat circulates the aqueous mixture comprising the one or more oils to afirst surface of the one or more membrane or membrane contactors,wherein the one or more oils coalesce at the first surface of the one ormore membrane or membrane contactors; and a collection conduit or vesselfor a stream from a second surface of the one or more membrane ormembrane contactors, wherein the stream comprises the oils without theneed for a counterflowing recovery fluid. In another aspect, the aqueousmixture contains one or more organisms that include at least one ofintact cells, lysed cells, apoptotic cells, or necrotic cells, comprisestwo or more different organisms, comprise yeast, algae or bacteria orcomprise organisms capable of secreting oil or causing the accumulationof oil outside living cells. In another aspect, the aqueous slurrycontains one or more organisms that are genetically modified to renderthem capable of secreting hydrophobic components, organisms that arecapable of causing accumulation of the one or more hydrophobiccomponents outside living cells, organisms that are capable of causingaccumulation of the one or more hydrophobic components outside livingcells upon induction with one or more chemical probes, exogenous agents,or pharmaceuticals, or combinations thereof. In another aspect, themethod further comprises contacting the organism with chemical probes,exogenous agents, or pharmaceuticals, whereby the metabolism of the oneor more organism is modified, wherein at least one organism causesaccumulation of the one or more oils outside living cells. In anotheraspect, the system further contacting the one or more oils in the liquidsource to remove oil, then returning the aqueous slurry to a growthenvironment. In another aspect, the 45%, 50%, 55%, 60%, 65%, 70%, 75%,80%, 85%, 90%, 95%, 98%, 99% or 100% of the one or more insoluble oilsin the liquid source are recovered. In another aspect, the one or moremembrane or membrane contactors area selected from at least one ofpolyethylene, polypropylene, polyolefins, polyvinyl chloride (PVC),amorphous Polyethylene terephthalate (PET), polyolefin copolymers,poly(etheretherketone) type polymers, surface modified polymers, orsurface modified polymers modified chemically at one or more halogengroups by corona discharge or by ion embedding techniques. In anotheraspect, once the system is collecting oil, further comprising the stepof counterflowing a recovery fluid that comprises the same oil recoveredin the initial operation of the contactor.

Yet another embodiment of the present invention includes a system forimproving oil quality of a contaminated oil mixture, comprising: aconduit or vessel that comprises a source of contaminated oil; and amembrane contactor system comprising one or more membranes or membranecontactors each having a first surface that coalesces one or more oilsfrom the contaminants in the oil, wherein the membrane contactor systemseparates the contaminants from the oil and wherein the contaminantsinclude at least one of a lipophobic liquid, or a solid from thecontaminated oil. In one aspect, the contaminated oil is at least one ofan oil-rich stream, crude oil, transportation fuel, heating oil, refinedpetroleum products, petrochemicals, bio-oils, renewable oils, vegetableoils, reclaimed oils, motor oils, transformer oils, lubricating oils,waste oils or oil sands tailings. In another aspect, the membranecontactor is defined further as a hydrophobic membrane or membranemodule that comprises hollow fiber microporous membranes selected fromat least one of hydrophobic hollow fiber membrane comprisespolyethylene, polypropylene, polyolefins, polyvinyl chloride (PVC),amorphous Polyethylene terephthalate (PET), polyolefin copolymers,poly(etheretherketone) type polymers, surface modified polymers, orsurface modified polymers comprise polymers modified chemically at oneor more halogen groups by corona discharge or by ion embeddingtechniques. In another aspect, the oil separated from the contaminatedoil by the membrane contactor is mixed with a counterflowing fluid,wherein the at least one counterflowing fluid selected from hydrophobicliquids, alkanes such as hexane, aromatic solvents such as benzene,toluene, ethers, diethyl ether, halogenated solvents such as chloroform,dichloromethane, ethyl acetate, esters, or the same oil without thecontaminants.

Another embodiment of the present invention includes a method forremoving contaminants from a contaminated oil comprising the steps of:obtaining a contaminated oil that comprises oil and lipophobiccontaminants; coalescing the oil from the contaminated oil onto a firstsurface of one or more membrane contactors; collecting the coalesced oilfrom the contaminated oil; and separately collecting the contaminantsfrom the water stream with a membrane contactor system in the presenceof solids small enough to pass into the one or more membrane contactors,wherein the membrane contactor removes the lipophobic contaminants fromthe contaminated oil. In one aspect, the lipophobic contaminants arefrom at least one of oily water, oil industry waste streams, oilcontaminated water or brine, wastewater, oil containing drainage water,water contaminated with oil, seawater contaminated with oil, brinecontaminated with oil, industrial effluents that comprise oil, naturaleffluents that comprise oil, drilling mud, tailing ponds, leach residue,produced water, oil sands tailing, frac water, connate water, anoil/water/solid mixture, a gravity separated oil/water/solid mixture,water-oil mixtures, aqueous slurries, aqueous slurries comprising brokencells, live cells or organisms, biocellular mixtures, lysed cellularpreparations, or lipophobic contaminants from a bioreactor, that havenot been separated or have been separated by at least one of gravity,centrifugal, centripedal, or hydrocyclone separation. In another aspect,the contaminated oil is processed by the system within 1, 2, 4, 6, 8,12, 24, 26, 48 or 72 hours from preparation. In another aspect, themembrane contactor is defined further as a hydrophobic membrane ormembrane module that comprises hollow fiber microporous membranesselected from at least one of polyethylene, polypropylene, polyolefins,polyvinyl chloride (PVC), amorphous Polyethylene terephthalate (PET),polyolefin copolymers, poly(etheretherketone) type polymers, surfacemodified polymers, or surface modified polymers comprise polymersmodified chemically at one or more halogen groups by corona discharge orby ion embedding techniques. In another aspect, the oil coalesced on thefirst surface of the membrane contactor is collected on the secondsurface of the membrane contactor with a counterflowing fluid, whereinthe at least one counterflowing fluid selected from hydrophobic liquids,alkanes such as hexane, aromatic solvents such as benzene, toluene,ethers such as diethyl ether, halogenated solvents such as chloroform,dichloromethane, and esters such as ethyl acetate. In another aspect,the counterflowing oil is oil recovered from a similar liquid sourceusing the membrane contactor without a recovery fluid or recovered byanother method.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the features and advantages of thepresent invention, reference is now made to the detailed description ofthe invention along with the accompanying figures and in which:

FIG. 1 is a schematic showing the method and the algal oil recoveryprinciple as described in the embodiments of the present invention;

FIG. 2 is a schematic of a general algal oil production process;

FIGS. 3A and 3B shows photographs of an algal cell prior to (3A) andafter lysing (3B);

FIGS. 3C and 3D shows photographs of algal cells prior to (3C) and afterlysing (3D);

FIG. 4 is a flow diagram of a general algae oil recovery process;

FIG. 5 is a flow diagram of the novel algal oil recovery process (withsolvent) of the present invention;

FIG. 6 is a flow diagram of the novel algal oil recovery process(without solvent) of the present invention;

FIG. 7 is a schematic of the Liqui-Cel extra flow microporous hollowfiber membrane contactor;

FIG. 8 is a HPLC trace (chromatogram) of oil obtained using hollow fibermembrane recovery of oil from a lysed suspension of Nanochloropsis. Twomain peaks are seen in this sample, the first is a mixture of variouslong chain hydrocarbons and the second is a triglyceride;

FIG. 9 shows an alternative process where a solid-liquid-liquid emulsionpotentially derived from a dispersive extraction is fed to theshell-side of the microporous hollow fiber membrane for the purpose ofseparating the two liquids;

FIG. 10 is a schematic showing the method and the oil/water separationprinciple for recovery/removal of oil from an oil/water mixture asdescribed in the embodiments of the present invention;

FIG. 11 is a schematic showing the method and the oil/water separationprinciple for exclusion of water from a water/oil mixture;

FIG. 12 is a flow diagram of the equipment used to create oil watermixtures and separate it;

FIG. 13 is an example of oil/water separation from a ˜12% oil in watermixture without a recovery fluid;

FIG. 14 is a comparison of oil/water separation with and without arecovery fluid;

FIG. 15 is an example of oil flux through the tubes of the membrane withand without a recovery fluid;

FIG. 16 is an example of the relationship between pressure and flux ratefor oil;

FIG. 17 is an example of oil removal from oilfield waste water without arecovery fluid;

FIGS. 18A and 18B are examples of water exclusion from oil.

DETAILED DESCRIPTION OF THE INVENTION

While the making and using of various embodiments of the presentinvention are discussed in detail below, it should be appreciated thatthe present invention provides many applicable inventive concepts thatcan be embodied in a wide variety of specific contexts. The specificembodiments discussed herein are merely illustrative of specific ways tomake and use the invention and do not delimit the scope of theinvention.

To facilitate the understanding of this invention, a number of terms aredefined below. Terms defined herein have meanings as commonly understoodby a person of ordinary skill in the areas relevant to the presentinvention. Terms such as “a”, “an” and “the” are not intended to referto only a singular entity, but include the general class of which aspecific example may be used for illustration. The terminology herein isused to describe specific embodiments of the invention, but their usagedoes not delimit the invention, except as outlined in the claims.

As used herein, the term “aqueous slurry” encompasses water basedliquids containing any of the following in any combination; insolubleoils (hydrocarbons and hydrocarbon-rich molecules of commercial value),living, dead, damaged and/or broken cells (or not), proteins and othercellular debris, including sugars, DNA, RNA, etc. The slurry may alsocontain a solvent that was used to pre-treat cells to liberate compoundsof interest.

As used herein, the term “oil” refers to a single hydrocarbon orhydrocarbon-rich molecule including a complex mixture of lipids,hydrocarbons, free fatty acids, triglycerides, aldehydes, etc. The termoil also includes, e.g., C₈ (jet fuel compatible), C₆₀ (motor oilcompatible) and oils that are odd- or even-chain oils (and mixturesthereof), e.g., from C₆ to C₁₂₀. Some compounds are pure hydrocarbons,some have oxygen. Oil also comprises hydrophobic or lipophiliccompounds.

As used herein, the term “pumping” includes all methods of pumping,propelling, or feeding fluid from one location to another employinghoses, lines, tubes, ducts, pipes, or pipelines including underpressure. It also includes gravity flow of fluid.

Unlike the prior art, the present invention is based on the discoverythat it is possible to feed two immiscible liquids on one side of ahollow fiber membrane, e.g., the shell-side, to cause separation of oilsusing coalescence versus liquid extraction. By contrast, the prior art,e.g., U.S. Pat. Nos. 3,956,112; 5,252,220; and 6,436,290, are feedingone immiscible liquid on the shell side.

U.S. Pat. No. 3,956,112, issued to Lee, et al., is directed to amembrane solvent extraction. Briefly, this patent is said to describe amembrane solvent extraction system that is used to separate a dissolvedsolute from one liquid referred to as the carrier and into a secondliquid, which is immiscible with the carrier and is referred to as thesolvent. Therefore, the hollow fiber membrane is used to extract asolute through a solvent swollen membrane from one solvent liquid phaseto the extracting solvent liquid with direct contact between the liquidphases only within the porous walls. The membrane extraction method haspotential advantages over conventional solvent extraction in that itdoes not require a density difference and provides a large amount ofcontact area. The membrane extraction contactor and may be applied tomolecular diffusion based mass transfer separation processes as themechanism in separation, purification, pollutant removal and recoveryprocesses. The Lee patent relies on liquid extraction, as the solventswells the membrane filling the pores and providing a diffusionalprocess to extract a dissolved solute from an immiscible liquid carrier.

The present invention uses coalescence to achieve the transfer acrossthe membrane, the component to be removed is essentially insoluble inthe feed and we are recovering only the insoluble liquid. In liquidextraction, the component to be removed is dissolved in the feed and thedissolved material is recovered.

In the present invention, the second immiscible liquid (hydrocarbon) isremoved from the aqueous feed by coalescence on the surface of thefiber. By contrast, the prior art is removing a dissolved solute(possibly a hydrocarbon).

Finally, unlike the prior art, the present invention does not rely ondiffusional mass transfer, but rather, wettability of the insolubleliquid on the fiber. The liquid extraction of the prior art relies onliquid-liquid partitioning, diffusional mass transfer and mass transferresistances.

In conventional liquid-liquid extraction and coalescing processesinvolving large drops of oil (greater than 1,000 microns), the mixingand separation of the oil and water phases by a dispersive process isroutinely practiced with relative ease. However, when the oil drops aresignificantly smaller in diameter (less than 10 microns) and solids arepresent, the complete separation of the immiscible liquids is extremelydifficult, if not impossible using dispersive methods routinelypracticed for larger oil droplets. When routine methods are applied totry to recover small oil droplets from water in the presence of solids(such as cells or cell debris), a solid-liquid-liquid emulsion layer iscreated resulting in an incomplete and inefficient separation of the twoliquids. Therefore a new process is required that will allow for a moreefficient separation and elimination of the solid-liquid-liquid-emulsionproblem. The process of the present invention enables the recovery ofmicron and submicron sized insoluble oil drops from an aqueous slurryutilizing a novel non-dispersive process.

A non-dispersive process promotes a one-way flow of specific compoundsinto and through a membrane to remove the compounds from the shell sidefeed to the tube side. A non-dispersive separation process is currentlyused to remove dissolved gases from liquids such as the removal ofdissolved oxygen from water to produce ultra pure water for themicroelectronics industry. The present invention is a first successfuldemonstration of the application of non-dispersive processes to recoverinsoluble oil from water or aqueous slurries. The non-dispersive processdisclosed herein uses a microporous hollow fiber membrane composed ofhydrophobic fibers. The aqueous slurry containing the insoluble oil isfed on the shell-side of the hollow fiber module and ahydrocarbon-appropriate solvent, for example, a biodiesel, or similaroil recovered in previous application of the described process is fed onthe tube side of the hollow fiber module as a recovery fluid. Theaqueous phase passes around the outside of the large surface area ofhydrophobic fibers containing the hydrophobic recovery fluid as itpasses through and eventually out of the module. As the aqueous liquidwith the insoluble oil drops passes through the module, the insolubleoil droplets coalesce on to the walls of the hydrophobic fibers anddissolve into the hydrocarbon-appropriate recovery fluid on the tubeside of the module and are carried out of the module with the recoveryfluid. In this process, the tube side recovery fluid does not makeprolonged contact with the aqueous phase or disperse into the aqueousphase. The absence of this mixing as hypothesized by the inventorsprevents the formation of a solid-liquid-liquid emulsion, when solidswere present, allowing insoluble oil to be recovered efficiently from anaqueous slurry containing solids. The above hypothesis was successfullydemonstrated herein to efficiently recover insoluble oil from an aqueousmixture including cells without the formation of a solid-liquid-liquidemulsion.

In typical membrane filtration processes, small amounts of solidsquickly build up on the surface of the membrane (commonly calledmembrane fouling) reducing the efficiency and cost effectiveness of thefiltration process. In the process discovered and disclosed herein usingthe microporous hollow fiber membrane module, membrane fouling is not aconcern within specific operating parameters. The present inventionshows that if the module is operated using hydrophilic cells that aresmall enough to pass through the dimensions of the module, and anappropriate pressure differential is maintained between the aqueousfluid and recovery fluid, then the hydrophilic cells flow through themodule and are repelled from the surface of the membrane because themembrane is coated with a hydrophobic recovery fluid. The resultspresented herein at the prescribed operating conditions do not indicateany evidence of membrane fouling.

The novel recovery process of the present invention utilizes anon-dispersive method to coalesce and recover an insoluble oil from anaqueous slurry. The technique utilizes a microporous hollow fibermembrane contactor. The inventors have tested the Liqui-Cel Extra FlowContactor, commercially used for gas/liquid contacting, to obtain >80%recovery efficiency and process concentrates up to 10% bio-cellularsolids without membrane fouling. The novel technique of the presentinvention utilizes the large coalescing area provided by the surface ofthe microporous hollow fibers when filled with a hydrophobic recoveryfluid and minimizes the actual contact of the solvent with the (e.g.yeast) biomass and aqueous phase.

The novel recovery process described herein can be coupled with avariety of appropriate recovery fluids for recovery of insolublecompounds, depending upon the types of compound or compounds to berecovered. The choice of recovery fluid will impact both the sub-set ofcompounds recovered from the aqueous slurry as well as the downstreamsteps needed to economically and efficiently use compounds from therecovery fluid. Differential recovery of desired molecules, for example,recovery of non-polar oils, but not more polar oils, can be achieved bychoice of recovery fluid. Segregation of non-polar oils from polar oils,specifically polar oils containing phosphorous (e.g., phospholipids), ishighly advantageous as phosphorus containing compounds complicate boththe refining and transesterification processes used to createtransportation fuels.

Downstream steps needed to recover desired molecules from the recoveryfluid are also application specific. If heptane is used as the recoveryfluid, compounds of interest may be recovered by distillation withoutthe need of a steam stripper. If biodiesel (Fatty Acid Methyl Ester[FAME]) is used as the recovery fluid, e.g., recovered oils may notrequire processing prior to transesterification to FAME. Importantly,the present invention can also use a “self” oil that has been previouslyrecovered from an aqueous slurry as the recovery fluid therebycompletely eliminating the need and expense of having to separate therecovered compounds from the recovery fluid. In this application, therecovery fluid is a quantity of oil derived from previously processedaqueous slurry or extracted by a different method. The microporoushollow fiber membrane contactor as described in the present invention issmall, portable, economical and is capable of handling large aqueousslurry feed rates.

In another embodiment, the present invention describes a method ofrecovering one or more hydrocarbons or hydrocarbon-rich molecules (e.g.,farnesene, squalane, aldehydes, triglycerides, diglycerides, etc.) orcombinations thereof, from an aqueous preparation using one or morehydrophobic membranes or membrane modules. Without limiting the scope ofthe invention, an example includes recovery of hydrocarbon andhydrocarbon-rich molecules produced by microbial fermentation. Microbialfermentation processes are described in which organisms including algae,yeast, E. coli, fungi, etc. are used to metabolize carbon sources (e.g.,sugars, sugarcane bagasse, glycerol, etc.) into hydrocarbons andhydrocarbon-rich molecules that are secreted from (or accumulate within)the cells. Such organisms are expected, by design, to produce physicallysmall oil droplets; the inventors hypothesized that these droplets willnot readily resolve from water by gravity alone and that the processdescribed herein will be immediately applicable to recover insolubleoils produced by microbial platforms. The companies commercializingmicrobial fermentation to oil technologies have implied that therecovery of the oil product is trivial, but emerging company disclosuresand scientific data suggest recovering the oil from the aqueous growthmedia is a mission-critical problem. Technologies currently in use, fore.g. centrifugal force sufficient to pellet E. coli cells are notsufficient to break the oil/water emulsion that is created in theaqueous growth media by the hydrocarbon-producing E. coli.

In addition to the steps listed herein above the method of the presentinvention further involves the steps of collecting the one or morerecovered algal lipid components, algal oils or both in a collectionvessel, recycling the separated solvent by pumping through the one ormore membranes or membrane modules to process a subsequent batch oflysed algae, converting the one or more recovered algal lipidcomponents, algal oils or both in the collection vessel to Fatty AcidMethyl Esters (FAMEs) or a biodiesel by transesterification oralternatively, refinery-based processing such as hydrocracking orpyrolysis, and processing the first stream comprising the algal biomassby drying the algal biomass to be optionally used as animal feed,feedstock for chemical production, or for energy generation. In theevent one or more solvents are used as the recovery fluids, the methodincludes an optional step for separating the one or more recovered algallipid components, algal oils or both from the one or more solvents. Thelysed algal preparation used in the method of the present inventioncomprises a concentrate, a slurry, a suspension, a dispersion, anemulsion, a solution or any combinations thereof.

In one aspect the hydrophobic membrane or membrane module comprisesmicroporous hollow fiber membranes, selected from polyethylene,polypropylene, polyolefins, polyvinyl chloride (PVC), amorphousPolyethylene terephthalate (PET), polyolefin copolymers,poly(etheretherketone) type polymers, surface modified polymers,mixtures or combinations thereof. The surface modified polymers comprisepolymers modified chemically at one or more halogen groups or by coronadischarge or by ion embedding techniques. In another aspect of themethod of the present invention the algae are selected from the groupconsisting of the diatoms (bacillariophytes), green algae(chlorophytes), blue-green algae (cyanophytes), golden-brown algae(chrysophytes), haptophytes, Amphipleura, Amphora, Chaetoceros,Cyclotella, Cymbella, Fragilaria, Hantzschia, Navicula, Nitzschia,Phaeodactylum, Thalassiosira Ankistrodesmus, Botryococcus, Chlorella,Chlorococcum, Dunaliella, Monoraphidium, Oocystis, Scenedesmus,Nanochlorposis, Tetraselmis, Chlorella, Dunaliella, Oscillatoria,Synechococcus, Boekelovia, Isochysis and Pleurochysis.

In yet another aspect of the method of the present invention, when usingone or more counterflowing recovery fluids, these may comprisehydrophobic liquids, alkanes such as hexane, aromatic solvents such asbenzene, toluene, ethers such as diethyl ether, halogenated solventssuch as chloroform, dichloromethane, and esters such as ethyl acetate.In one aspect the counterflowing non-polar oil comprises algal oils,components of biodiesels selected from monoglycerides, diglycerides,triglycerides, and fatty acid methyl esters.

The present invention describes a method for recovering algae oil fromlysed algae concentrate using hydrophobic microporous hollow fibermembrane followed by recovery of the algal oil using a recovery fluidwhich can be a solvent, a hydrophobic liquid, a biodiesel, an algal oilor mixtures thereof. The technique of the present invention does notrequire dispersive contacting of the lysed algae concentrate andrecovery fluid. The use of a hydrophobic microporous hollow fibermembrane provides a non-dispersive method of coalescing and recoveringthe algal oil. The lysed algae concentrate is fed on the shell sidewhile algal oil or the recovery fluid is fed on the fiber side. Therecovery fluid acts to sweep and remove the coalesced oil within thetube surface of the hollow fibers. A simple schematic representation ofthe method of the present invention is depicted in FIG. 1.

FIG. 1 shows an algal oil recovery unit 100. The unit 100 comprises ahousing 102, within which is contained a membrane module 104 comprisinga plurality of microporous hollow fiber membrane units depicted as 104a, 104 b, and 104 c. The unit has two inlet ports 106 and 108. The lysedalgal preparation is fed (pumped) through port 106. A recovery fluid ispumped through inlet port 108. The recovery fluid can be a solvent, abiodiesel, an algal oil or mixtures thereof. The algal preparationcounterflows with the recovery fluid flowing inside the microporoushollow fiber membranes 104 a, 104 b, and 104 c. The algal oils or lipidcoalesce on the surface of the hollow fiber membranes and are swept byand recovered by the recovery fluid and exit the unit 100 through theoutlet port 110. The exit stream is taken for further processing (e.g.solvent recovery) if necessary. The recovery fluid flows out of the unit100 through port 112.

The method of the present invention using a compatible mixture as therecovery fluid eliminates the need of a distillation system or astripper to recover the solvent thereby reducing the capital andoperating cost of the overall oil recovery process.

A wide variety of organisms can be used to generate oils and lipids thatcan be recovered with the present invention. Non-limiting examples ofalgae and microalgae may be grown and used with the present inventionincluding one or more members of the following divisions: Chlorophyta,Cyanophyta (Cyanobacteria), and Heterokontophyt. Non-limiting examplesof classes of microalgae that may be used with the present inventioninclude: Bacillariophyceae, Eustigmatophyceae, and Chrysophyceae.Non-limiting examples of genera of microalgae used with the methods ofthe invention include: Nannochloropsis, Chlorella, Dunaliella,Scenedesmus, Selenastrum, Oscillatoria, Phormidium, Spirulina, Amphora,and Ochromonas. Non-limiting examples of microalgae species that can beused with the present invention include: Achnanthes orientalis,Agmenellum spp., Amphiprora hyaline, Amphora coffeiformis, Amphoracoffeiformis var. linea, Amphora coffeiformis var. punctata, Amphoracoffeiformis var. taylori, Amphora coffeiformis var. tenuis, Amphoradelicatissima, Amphora delicatissima var. capitata, Amphora sp.,Anabaena, Ankistrodesmus, Ankistrodesmus falcatus, Boekeloviahooglandii, Borodinella sp., Botryococcus braunii, Botryococcussudeticus, Bracteococcus minor, Bracteococcus medionucleatus, Carteria,Chaetoceros gracilis, Chaetoceros muelleri, Chaetoceros muelleri var.subsalsum, Chaetoceros sp., Chlamydomas perigranulata, Chlorellaanitrata, Chlorella antarctica, Chlorella aureoviridis, Chlorellacandida, Chlorella capsulate, Chlorella desiccate, Chlorellaellipsoidea, Chlorella emersonii, Chlorella fusca, Chlorella fusca var.vacuolate, Chlorella glucotropha, Chlorella infusionum, Chlorellainfusionum var. actophila, Chlorella infusionum var. auxenophila,Chlorella kessleri, Chlorella lobophora, Chlorella luteoviridis,Chlorella luteoviridis var. aureoviridis, Chlorella luteoviridis var.lutescens, Chlorella miniata, Chlorella minutissima, Chlorellamutabilis, Chlorella nocturna, Chlorella ovalis, Chlorella parva,Chlorella photophila, Chlorella pringsheimii, Chlorella protothecoides,Chlorella protothecoides var. acidicola, Chlorella regularis, Chlorellaregularis var. minima, Chlorella regularis var. umbricata, Chlorellareisiglii, Chlorella saccharophila, Chlorella saccharophila var.ellipsoidea, Chlorella salina, Chlorella simplex, Chlorella sorokiniana,Chlorella sp., Chlorella sphaerica, Chlorella stigmatophora, Chlorellavanniellii, Chlorella vulgaris, Chlorella vulgaris fo. tertia, Chlorellavulgaris var. autotrophica, Chlorella vulgaris var. viridis, Chlorellavulgaris var. vulgaris, Chlorella vulgaris var. vulgaris fo. tertia,Chlorella vulgaris var. vulgaris fo. viridis, Chlorella xanthella,Chlorella zofingiensis, Chlorella trebouxioides, Chlorella vulgaris,Chlorococcum infusionum, Chlorococcum sp., Chlorogonium, Chroomonas sp.,Chrysosphaera sp., Cricosphaera sp., Crypthecodinium cohnii, Cryptomonassp., Cyclotella cryptica, Cyclotella meneghiniana, Cyclotella sp.,Dunaliella sp., Dunaliella bardawil, Dunaliella bioculata, Dunaliellagranulate, Dunaliella maritime, Dunaliella minuta, Dunaliella parva,Dunaliella peircei, Dunaliella primolecta, Dunaliella salina, Dunaliellaterricola, Dunaliella tertiolecta, Dunaliella viridis, Dunaliellatertiolecta, Eremosphaera viridis, Eremosphaera sp., Effipsoidon sp.,Euglena spp., Franceia sp., Fragilaria crotonensis, Fragilaria sp.,Gleocapsa sp., Gloeothamnion sp., Haematococcus pluvialis, Hymenomonassp., lsochrysis aff galbana, lsochrysis galbana, Lepocinclis,Micractinium, Micractinium, Monoraphidium minutum, Monoraphidium sp.,Nannochloris sp., Nannochloropsis salina, Nannochloropsis sp., Naviculaacceptata, Navicula biskanterae, Navicula pseudotenelloides, Naviculapelliculosa, Navicula saprophila, Navicula sp., Nephrochloris sp.,Nephroselmis sp., Nitschia communis, Nitzschia alexandrine, Nitzschiaclosterium, Nitzschia communis, Nitzschia dissipata, Nitzschiafrustulum, Nitzschia hantzschiana, Nitzschia inconspicua, Nitzschiaintermedia, Nitzschia microcephala, Nitzschia pusilla, Nitzschia pusillaelliptica, Nitzschia pusilla monoensis, Nitzschia quadrangular,Nitzschia sp., Ochromonas sp., Oocystis parva, Oocystis pusilla,Oocystis sp., Oscillatoria limnetica, Oscillatoria sp., Oscillatoriasubbrevis, Parachlorella kessleri, Pascheria acidophila, Pavlova sp.,Phaeodactylum tricomutum, Phagus, Phormidium, Platymonas sp.,Pleurochrysis carterae, Pleurochrysis dentate, Pleurochrysis sp.,Prototheca wickerhamii, Prototheca stagnora, Prototheca portoricensis,Prototheca moriformis, Prototheca zopfii, Pseudochlorella aquatica,Pyramimonas sp., Pyrobotrys, Rhodococcus opacus, Sarcinoid chrysophyte,Scenedesmus armatus, Schizochytrium, Spirogyra, Spirulina platensis,Stichococcus sp., Synechococcus sp., Synechocystisf, Tagetes erecta,Tagetes patula, Tetraedron, Tetraselmis sp., Tetraselmis suecica,Thalassiosira weissflogii, and Viridiella fridericiana.

Other sources for biomass can be a wild type or genetically modifiedfungus. Non-limiting examples of fungi that may be used with the presentinvention include: Mortierella, Mortierrla vinacea, Mortierella alpine,Pythium debaryanum, Mucor circinelloides, Aspergillus ochraceus,Aspergillus terreus, Penicillium iilacinum, Hensenulo, Chaetomium,Cladosporium, Malbranchea, Rhizopus, and Pythium. As the source ofbiomass is not limited using the devices and methods of the presentinvention can be wild type or genetically modified yeast. Non-limitingexamples of yeast that can be used with the present invention includeCryptococcus curvatus, Cryptococcus terricolus, Lipomyces starkeyi,Lipomyces lipofer, Endomycopsis vernalis, Rhodotorula glutinis,Rhodotorula gracilis, Candida 107, Saccharomyces paradoxus,Saccharomyces mikatae, Saccharomyces bayanus, Saccharomyces cerevisiae,any Cryptococcus, C. neoformans, C. bogoriensis, Yarrowia lipolytica,Apiotrichum curvatum, T. bombicola, T. apicola, T. petrophilum, C.tropicalis, C. lipolytica, and Candida sp., e.g., Candida albicans.

The biomass can even be any bacteria that generate lipids, oils,proteins, and carbohydrates, whether naturally or by geneticengineering. Non-limiting examples of bacteria that can be used with thepresent invention include Escherichia coli, Acinetobacter sp. anyactinomycete, Mycobacterium tuberculosis, any streptomycete,Acinetobacter calcoaceticus, P. aeruginosa, Pseudomonas sp., R.erythropolis, N. erthopolis, Mycobacterium sp., B., U. zeae, U. maydis,B. lichenformis, S. marcescens, P. fluorescens, B. subtilis, B. brevis,B. polmyma, C. lepus, N. erthropolis, T. thiooxidans, D. polymorphis, P.aeruginosa and Rhodococcus opacus.

While algae make oil there is no simple and economical method forextracting the oil directly from an aqueous slurry. Drying algae isusually needed for solvent extraction and the biomass is exposed totoxic solvents. Other methods such as supercritical extraction areuneconomical for commodity products such as fuel. Solvent extraction issomewhat promising but requires distillation of an extract to separatethe solvent from the oil. Also, a steam stripper is usually required torecover the residual solvent dissolved or entrained within the exitingalgal concentrate. The solvent extraction technique requires contactorequipment or phase separation equipment, a distillation system and asteam stripper along with varying heat exchangers, surge tanks andpumps. Also steam and cooling water are required. The process describedherein only requires a membrane system with pumps and tanks; the oil iscoalesced, not extracted. No steam or cooling water is required.

Processing Alternatives: After selection of the appropriate solvent, thenext step is to determine whether to extract algae oil from “wet” or“dry” algae. The “dry” process requires dewatering and evaporating thewater from the algae biomass and then lysing the algae. Lysing is aprocess of breaking the cell wall and opening the cell. Solvent may becontacted with the dry algae in special counter current leachingequipment. The solvent and extracted algae oil is separated in a vacuumdistillation tower or evaporator. The remaining algae biomass withresidual solvent is fed to a special evaporator to remove and recoverthe solvent and to dry the algae biomass again. The “dry” processsuffers from having to dry the algae a second time when the solvent mustbe evaporated away, handling a high solids stream in multiple steps, andpotentially leaving solvent in the residual algae solids.

The “wet” process requires lysing and extraction of the algaeconcentrate. The wet process requires an excellent lysing techniquefollowed by a solvent extraction process, which provides adequate masstransfer area for dissolving/coalescing the non-polar lipids. The “wet”process offers the advantages of drying the algae only once and leavingless residual solvent in the algae biomass. To minimize the processingcost, the “wet” process appears to offer significant advantages.

The present invention focuses on the “wet” process and the novelnon-dispersive contactor used to coalesce and dissolve the desirablenon-polar lipids.

As shown in FIG. 2 a complete extraction process 200 begins with the oilextraction step 212 followed by the algae concentration 208 and lysing210 steps. After growing and initial harvesting under sunlight 204, fromthe pond 202 the dilute algae feed is concentrated significantly. Themicrobes such as the algae, media and/or water are returned at step 214.The typical algae concentration obtained from the pond 202 generallyranges from 100 to 300 mg dried algae/liter of solution. The goal of theconcentration step 208 is to remove and recycle the water 214 back tothe pond. Concentration methods 208 vary from centrifugation toflocculation/settling of the algae. To maximize lysing and oil recoveryefficiency, it is important that concentrate being fed for lysing is notflocculated. After the concentration step 208, the algae concentrate issent to the lysing 210 processing step where the algae cell ismechanically or electromechanically broken, thus exposing and freeingthe non-polar oil. Various techniques may be used to mechanically orelectrically compress and decompress to break the cell. In general afterlysing, 212 the algae cell can be disintegrated or opened-up as shown inFIG. 3. FIGS. 3A and 3C shows photographs of an alga cell prior tolysing and FIGS. 3C and 3D show photographs of algal cells prior afterlysing.

Once the oil has been freed from inside the algae cell, the oil will notsimply separate from the cellular biomass due to density differences.Also since the equivalent diameters of most microalgae are extremelysmall and on the order of 1-5 microns, the oil drop diameter is oftenmuch less than 1 micron. Such oil drops do not rise or coalesce withother drops very well and can form a stable emulsion. When solid algaebiomass 216 is added to the mixture, the recovery of the oil is evenmore difficult. Therefore simple gravitational phase settling is not aviable oil separation option after lysing.

After lysing, the algae concentrate is fed to the separations step 212where algae oil 220 is separated from the wet algal biomass 216 toproduce fuel 214. The biomass 216 may be sent for further drying andwill be used for animal feed or processed further for energy generationapplications.

As shown in FIG. 4, the typical solvent extraction process involves 1)an extraction step to recover algae oil from the lysed biomass, 2) avacuum distillation or evaporation step to separate the oil and solventwhere the solvent is returned to step 1, and 3) if necessary, steamstripping step to recover the dissolved and entrained solvent leavingthe extraction step with the algal biomass.

FIG. 4 a flow diagram 400 of a general algae oil extraction processusing a conventional dispersive extraction column 406. Lysed algalconcentrate 402 and solvent 404 is fed to a column extractor 406 toextract the algal oils and lipids 408. Stream 406 a comprises thesolvent 404 containing the algal oils and lipids. Stream 406 a is thenfed to a vacuum distillation unit 408 to recover the solvent 404 and thealgal oil 410. The separated solvent without any oil or otherconstituents 404 is fed back to the extractor 406. In the event it needsfurther purification (separation), the solvent 404 is fed back to thevacuum distillation unit 408 (via stream 408 a). A second stream 406 bfrom the extractor 406 comprises the algal biomass, solids, and residualsolvent. Stream 406 b is passed through a stream stripper 412, toseparate the wet biomass 418 and other solids from the solvent 404. Thewet biomass 418 is subjected to further drying. The recovered solvent414 is collected in a decanting vessel 416 before being recycled 420back to the extractor 406 via stream 414 a and can be controlled withvalve 424. A second stream 414 b from the vessel 416 recycles anydissolved solvent in condensed steam 414 back to the stream stripper412.

Extraction Processing and Equipment: The desired extraction process foralgae oil recovery must satisfy certain requirements and avoid potentialdeficiencies for economic recovery. There are several “wet” extractionprocesses for oil recovery that are technically feasible but are notnecessarily economical. Minimal oil recovery costs are critical if theultimate use of the recovered algae oil is fuel.

The optimum oil extraction process should include: (i) processing abio-cellular aqueous slurry containing oil, (ii) using a non-polarsolvent or extracted oil with extremely low miscibility in water, (iii)using a solvent (if necessary), that easily separates from the oil, (iv)using extraction equipment that can handle high processing feed ratesand easily scaled-up, (v) using extraction equipment that minimizes theentrainment of solvent into the biomass, (vi) using extraction equipmentthat provides a high contact area for mass transfer and non-polar lipidcoalescence, (vii) using extraction equipment capable of handlingconcentrated algae feeds and not be irreversibly fouled by algae solids,(viii) using extraction equipment that is relatively compact andpotentially portable to allow transport to different algae productionsites, and (ix) using extraction equipment that is readily available,inexpensive and safe.

Membrane based processes for separations have been in existence for along time. There are many types of membranes. Most membrane processeshowever use porous membranes wherein the membrane material performs aseparation as a result of differences in diffusion and equilibriumbetween chemical components and on the molecular level. The presentinventors however utilize a microporous membrane, which is usedcommercially in applications involving the transfer of gases to or froma liquid such as water. The microporous membranes function verydifferently from the porous membrane because of their relatively largepores. The microporous membranes do not truly separate chemicalcomponents on the molecular level like porous membranes do. The presentinvention relies on the coalescence of non-polar lipids present withinthe algae slurry to coalesce onto the hydrophobic surfaces provided bythe hollow fibers. The vast surface area of the membrane, combined withthe hydrophobic recovery fluid's ability to wet the membrane, creates asurface capable of coalescing small lipid droplets. Once coalesced intothe recovery fluid, the lipids are transported out of the membranethrough the inner tubes of the hollow fibers.

Membrane based Oil Recovery Process: For example, the application of amicroporous hollow fiber (MHF) membrane contactor as the optimalseparation equipment appears ideally suited for the recovery of algaeoil. The MHF contactor provides all of the optimum characteristicslisted previously. The application MHF contactor to algae oil recoveryis novel, minimizes solvent loss, eliminates need for the steamstripper, minimizes solids contamination, and is easy to operate. Theprocess does not involve dispersing a solvent into the algae biomass.The non-dispersive nature of the contactor is attractive in minimizingsolvent loss and thus potentially eliminating the need for a steamstripper. A recovery fluid typically comprising of either a solvent(such as hexane) or a hydrophobic liquid, or algal oil is circulatedthrough the hollow fibers for the recovery of the algal oils. Theapplication of the MHF contactor in conjunction with a recovery fluidcirculated through the microporous hollow fibers eliminates the need fora solvent and distillation column. The two oil extraction processingschemes with solvent and the recovery fluid are shown in FIGS. 5 and 6,respectively.

FIG. 5 is a schematic 500 depicting the novel algal oil recovery process(with solvent) of the present invention. The process comprises a MHFcontactor 502 comprising a plurality of microporous hollow fibermembranes 504 and a central baffle 506. Solvent 508 is fed (pumped)through the membrane fibers 504 and is contacted with the lysed algalconcentrate 512 contained in the shell portion of the MHF contactor 502.There are two exit streams from the contactor 502, an algal biomassstream 510 which is processed further (dried) and a solvent stream 508 awhich contains the recovered algal oils and lipids 516. The stream 508 ais passed through a vacuum distillation unit 514 to separate the oil 516from the solvent 508 and to recover the solvent 508 for recycle andreuse. Exit stream 508 b from the distillation unit 514 comprises puresolvent 508 which is recycled and fed to the contactor 502 to repeat theprocess and solvent requiring further separation and is recycled back tothe distillation unit 514. Exit stream 508 c from the distillation unit514 comprises the algal oils 516. A portion of this stream is vaporized(518 b) and returned to the distillation unit 514.

FIG. 6 is a schematic 600 depicting the novel algal oil recovery processof the present invention. The process comprises a MHF contactor 602comprising a plurality of microporous hollow fiber membranes 604 and acentral baffle 606. Non-polar algae oil 608 is fed (pumped) through themembrane fibers 604 and is contacted with the lysed algal concentrate612 contained in the shell portion of the MHF contactor 602. Thenon-polar algae oil functions to dissolved and sweep the coalesced oilfrom the algae concentrate. The non-polar oil 616 coalesces onto thehydrophobic fiber surface 604 and dissolves into oil contained in thewalls and the counterflowing oil phase 608 and can be removed. There aretwo exit streams from the contactor 602, an algal biomass stream 610which is processed further (dried) a stream 608 a which contains thealgal oils and lipids 616 that is collected in a tank 614. Part of theoil 616 can be removed from the tank 614 and fed to the contactor 602 torepeat the process.

Microporous hollow fiber contactors were initially developed in the1980s. These early studies focused on lab-scale prototype modulescontaining just a few fibers. These early studies promoted thepossibility of liquid-liquid extraction applications. The contacting oftwo immiscible liquids such as water and a non-polar solvent is uniquewith MHF contactors in that there is no dispersion of one liquid intoanother. This technology is sometimes referred to as non-dispersiveextraction. The hollow fibers are generally composed of a hydrophobicmaterial such as polyethylene or polypropylene. These hollow fiberscould be made of a different material but it should be hydrophobic toavoid fouling of the fiber surface with the algae solids which areusually hydrophilic. The solvent should be a hydrocarbon with a very lowsolubility in water and is pumped through the hollow fibers. As a resultof the hydrophobicity of the fiber material, the solvent will wet themicroporous fibers and fill the micropores. The aqueous-based fluid ispumped through the shell-side of the membrane contactor. To preventbreakthrough of the solvent into the shell-side, the shell or aqueousside is controlled at a higher pressure than the fiber or hydrocarbonside. This results in immobilizing a liquid-liquid interface in theporous walls of the hollow fibers. Unfortunately when these modules werescaled-up for liquid-liquid extraction, the performance was usuallydisappointingly poor. Further studies identified the poor efficiency wasa result of shell-side bypassing. An improved version (referred to asthe Liqui-Cel Extra Flow contactor) was developed which eliminated thepossibility of shell-side bypassing by incorporating a shell-sidedistributor. While the design eliminated the shell-side bypassing, thenew design eliminated true counter-current contacting. The overallperformance was improved somewhat relative to the original design.Nevertheless, the new design did not correct the fundamental limitationsof pore-side mass transfer resistance that would control mostcommercially significant extraction applications. As a result, only afew commercial liquid extraction applications using MHF contactingtechnology exist today.

Also, the MHF contactors often required expensive filter systems toavoid plugging with solids associated with most commercial liquid-liquidextraction processes. The Liqui-Cel contactor used in the presentinvention has been applied almost exclusively to commercial processesthat transfer a gas to or from a liquid such as oxygen stripping fromwater for the microelectronics industry.

No applications of the MHF contactors are known for enhancingcoalescence and removing of oil drops from water. Certainly noapplications of MHF technology are known for oil recovery from waterinvolving a significant solids concentration.

FIG. 7 is a schematic 700 of the Liqui-Cel extra flow microporous hollowfiber membrane contactor 702. The contactor 702 comprises a metallic orpolypropylene housing 706, wherein is contained a cartridge 708comprising a plurality of hydrophobic microporous hollow fibers 712,along with a distribution tube 710, a collection tube 716, and a centralbaffle 714. The housing 706 has 2 inlet ports (704 a and 704 b) and twooutlet ports 704 c and 704 d.

As shown in FIG. 7, the aqueous phase 718 is fed through the port 704 aon the shell-side while the solvent (or oil) phase 722 is fed on thefiber side through port 704 b. The non-polar lipids coalesce onto thehydrophobic surface and wet and dissolve into walls and into thecounterflowing solvent (or oil) phase. A higher pressure is maintainedon the aqueous side to prevent bleed through of the solvent (or oil)phase. However the shell-side pressure is kept below the breakthroughpressure which forces aqueous phase 718 into the solvent (or oil) phase722. The algae concentrate 718 and solvent feeds 722 could be operatedat room temperature or preheated up to 60° C. The solvent (or oil) phasealong with the recovered lipids or oils is removed through outlet port704 c, and the aqueous algal raffinate containing the algal biomass andother solids is removed through the port 704 d.

While not intuitive because of the presence of algae solids, the MHFcontactor appears ideal for recovering oil from lysed algae. The MHFcontactor provides: (i) high contact area for coalescence and masstransfer, (ii) processing of un-flocculated or deflocculated algaesolids, (iii) large flow capacities on the shell side, (iv) negligiblemass transfer resistance in the pore because of the high equilibriumdistribution coefficient of non-polar oils into non-polar solvent, and(v) low cost per unit of algae flow per unit as the contact area is 100×that for the conventional liquid extraction contactor (e.g. perforatedplate column).

The MHF contactor provides four significant advantages: (i) no densitydifference is required, (ii) no entrainment of solvent which mayeliminate the need for a stripping column when the proper solvent isselected, (iii) easy control of the liquid-liquid interface bycontrolling the pressures, (iv) extremely large area for coalescence ofsmall algae oil drops. The MHF contactor functions primarily as an oilcoalescer. The solvent acts to simply remove the coalesced oils from thesurface of the fibers, and (v) while not optimized, commercial MHFcontactor modules used for gas transfer are available and reasonablypriced. The Liqui-Cel Extra Flow contactor is a good example.

MHF Contactor Performance Data: The present inventors characterize theperformance of the MHF contactor for algal oil recovery. The objectivesof the studies were to determine the fraction of non-polar algaerecovered from the feed and determine if membrane plugging was observed.The 4-inch diameter Liqui-Cel Extra Flow Contactor, purchased fromMembrana [Part#G503], was used to recover algae oil from an actual lysedalgal concentrate (FIG. 7). Typical oil recoveries from experimentallylysed algae ranged from 45→80% for a single module. The results of thestudies are shown in Table 1. Differences in oil recoveries may beattributed to the lysing efficiency, polarity of the algae oil,differences in oil wettability and coalescence onto the membrane fibers.Membrane plugging is not observed when processing lysed algaeconcentrates where the algae is not flocculated or has beendeflocculated. A typical range of conditions associated with therecovery of non-polar algae oil is shown in Table 1. These data arebased on the processing of actual lysed algae. Since the non-polar oilrecovery efficiency is also affected by the lysing efficiency,controlled experiments were carried out where known quantities of canolaoil were injected into a re-circulating algae concentrate stream. In thefirst set of studies, heptane was re-circulated on the tube side as anon-polar oil specific recovery fluid. The results of these studies areshown in Table 2. In the initial small scale studies, 44-64% of theinjected oil volume was recovered by the microporous hollow fibermembrane when only 25 mLs of canola oil was injected. When a largerquantity of canola oil was injected (250 mL), more than 90% of theinjected oil volume was recovered as shown in Table 2. These dataprovide evidence that a fixed volume of oil is likely held up in thewalls of the hollow fibers. In a second set of studies using canola oilinjected into lysed algae concentrate, canola oil was re-circulatedthrough the hollow fiber tubes as a recovery fluid instead of heptane.As shown in Table 3, 93% of the 9 liters of injected canola oil wasrecovered, conclusively demonstrating that a “like” oil can be used as arecovery fluid. The second set of studies validates the mechanism thatthe process is based on coalescing and recovery of the oil drops fromthe aqueous slurry can be done using a “like” oil. The canola oil runsalso provide supporting data for the application of the non-dispersivemicroporous hollow fiber technology in removing residual oil fromproduced water, as canola oil/water emulsions are an acceptedexperimental proxy to mimic produced water in a laboratory setting. Theresults from Tables 2 and 3 indicate that oil recoveries approaching100% are possible. The walls of the hollow fibers will always containoil during processing.

TABLE 1 Typical algal oil recoveries from lysed algae with the MHFContactor. Parameter Overall Range Typical Range Algae concentration, wt% 0.01-15   1-5 Non-polar Oil in Algae, wt % 0.5-10  2-6 Algae Flowrate, gpm 0.5-2   0.5-1   Heptane Flow rate, gpm 0.04-0.07 0.07Non-polar Oil Recovery, % 40-90 70-80

TABLE 2 Results of controlled study using Heptane flowing through thetubes. Basis: Algae feed rate = 1,000 lbs/hr, Heptane feed rate = 50lbs/hr, Total mass of re-circulating algae = 50 lbs containingapproximately 1.5 wt % bio-cellular solids, Oil injection rate = 0.17lbs/hr. Test #1 #2 #3 #4 Oil Injected, ml 25 25 210 210 Oil Recovered,ml 11 16 198 188 Missing Oil 114 99 12 22 % Oil recovery 44 66 94 90

TABLE 3 Results of the solventless test with Canola oil flowing throughthe tubes. Shell-side and tube-side flows are re-circulated. Tube-SideCanola Oil Shell-Side 50 lbs of Algae Concentrate wt % bio-cellularsolids in algae Approximately 1.5 wt % Tube Side Flow rate 10-15 lbs/hrShell Side Flow rate 500, lbs/hr Canola Oil Injection Rate into Algae 3ml/min Run Time 72 hours % Recovery of Injected Canola Oil 93%

It should be noted that the algae concentrate feed or bio-cellular feedmust not contain flocculated algae or solids to prevent plugging withinthe membrane module. For the case of the MHF contactor described in thepresent invention, the minimum dimension for shell-side flow is 39microns which is greater than the size of most single alga. It is likelythat flocculated algae will eventually plug the shell-side of the MHFcontactor.

In a related and alternative process, the microporous membrane could beused to separate two liquids from a solid-liquid-liquid emulsion. Thesolid-liquid-liquid emulsion may have been derived from a process forrecovering oil from a bio-cellular aqueous feed using a dispersiveprocess. The microporous membrane hollow fiber contactor would allow thehydrocarbon liquid to “wet” and coalesce into the walls of the hollowfibers while preventing the hydrophilic solids or aqueous phase fromentering. Thus the hydrocarbon liquid will exit the membrane on the tubeside when an appropriate recovery fluid is employed, while the aqueousliquid and solids will exit on the shell-side. An alternative process isshown in FIG. 9.

The flow diagram 900 shown in FIG. 9 of the alternative algae oilextraction process comprises a dispersive extraction column 902, lysedalgal concentrate 904 and solvent 908 is fed to a dispersive extractorsuch as a column extractor, centrifugal type extractor or mixer-settler902. The solid-liquid-liquid emulsion (S-L-L) 912 from the column 902comprising algae-water-solvent is then fed to a shell-side of amicroporous membrane extractor (contactor) 910. Any solids (algalbiomass) from the column extractor 902 may be directly subjected tofurther processing (e.g. drying) as shown by step 914. The microporousmembrane hollow fiber contactor 910 allows the hydrocarbon liquid to“wet” and coalesce into the walls of the hollow fibers while preventingthe hydrophilic solids or aqueous phase from entering. The hydrocarbonliquid exits the membrane contactor 910 on the tube side when anappropriate recovery fluid (for e.g. solvent 908) is employed on thetube side, while the aqueous liquid and solids (algal biomass) will exiton the shell-side for further processing (e.g. drying) as shown by step914. The hydrocarbon liquid is then fed to a distillation unit 916 (heatexchangers associated with the distillation unit are shown as 918 and920) for removal of any residual solvent 906 and to recover the algaloil 924. The recovered solvent 906 may be circulated back into theprocess, for e.g. as the recovery fluid on the tube-side of the membranecontactor 910 or back to the dispersive extraction column 902.

The recovery fluid on the tube side can be tailored to enhance recoveryor selectively recover sub-sets of desired compounds, and leave others.Study data demonstrates that hydrocarbons and non-polar lipids areremoved using heptane or like oil and phospholipids are not.

To determine the composition of the recovered oil, the inventorsperformed a normal phase HPLC using a Sedex 75 evaporative lightscattering detector. As shown in FIG. 8, two main components weredetected in this particular sample of oil, the first peak correspondingto long chain hydrocarbons and the second corresponding totriglycerides. In some samples, 1,3 and 1,2 diglyceride have also beendetected.

FIG. 10 is a schematic showing the method and the oil/water separationprinciple for recovery/removal of oil from an oil/water mixture asdescribed in the embodiments of the present invention. In this mode ofoperation the present invention can be used for most oil/water mixturesthat are up to ˜90% oil by volume. The oil-water mixture emanating fromthe shell side may be further processed, for example with an additionalcontactor. In this embodiment, an oil/water mixture 1102 enters themembrane contactor 1100 and the oil coalesces on a first surface of themembrane contactor 1100. A recovery fluid 1104 that is in contact with asecond surface of the membrane contactor 1100 collects coalesced oil1108. An oil/water mixture without the coalesced oil 1106 and recoveredexits the membrane contactor 1100 and can be further processed bycontacting with the same or a different membrane contactor (not shown).

FIG. 11 is a schematic showing the method and the oil/water separationprinciple for exclusion of water from a water/oil mixture. In this modeof operation the present invention is appropriate for very low watercontent streams. With the shell side outflow capped, the excluded waterwill accumulate in the shell side of the module. The tube side oiloutflow rate can be used to indirectly monitor the accumulation of waterin the shell side. As water accumulates, the effective shell sidesurface area begins to decrease, leading to reduced tube side flows.Briefly opening the shell side outflow valve can purge the accumulatedwater and return the unit to high efficiency operation. In thisembodiment, an oil>>water mixture 1112 enters the membrane contactor1100 in which the oil is the primary portion of the liquid and the wateror other non-oil liquid is a lesser part of the mixture, and the oilcoalesces on a first surface of the membrane contactor 1100. A recoveryfluid 1104 that is in contact with a second surface of the membranecontactor 1100 collects coalesced oil 1108. An oil/water mixture withoutthe coalesced oil 1106 exits the membrane contactor 1100 and can befurther processed by contacting with the same or a different membranecontactor (not shown). In one embodiment, the amount of oil towater/non-oil liquid, volume to volume, may be 50:50, 60:40, 70:30,80:20, 90:10, 91:9, 92:8, 93:7, 94:6, 95:5, 96:4, 97:3, 98:2, 99:1,99.5:0.5, 99.6:0.4, 99.7:0.3, 99.8:0.2, and 99.9:0.1.

FIG. 12 is a flow diagram of a membrane contactor system 1200. In thisembodiment, the membrane contactor 1202 is a schematic 1200 depicting anovel oil recovery process of the present invention. The processcomprises a MHF contactor 1202 comprising a plurality of microporoushollow fiber membranes 1204 and a central baffle 1206. In onenon-limiting example of an oil, non-polar Algae oil 1208 is fed (pumped)through the membrane fibers 1204 and is contacted with the lysed yeastor algal oil concentrate 1212 contained in the shell portion of the MHFcontactor 1202. The non-polar oil 1216 coalesces onto the hydrophobicfiber surface 1204 and dissolves into oil contained in the walls and thecounterflowing oil phase 1208 and can be removed. There are two exitstreams from the contactor 1202, a yeast or algal biomass stream 1210which is processed further (dried) a stream 1208 a which contains theyeast or algal oils and lipids 1216 that is collected in a tank 1214.Part of the oil 1216 can be removed from the tank 1214 and fed to thecontactor 1202 to repeat the process. Media, nutrients, additionalorganisms (yeast or algae), liquid or other compositions can be providedfrom burettes 1219. Multiple pumps and valves may be used to control theflow of the various liquids and components.

FIG. 13 is a graph that shows the test results from the recovery of oilfrom a mixture created to test for oil recovery in the absence ofrecovery fluid at constant pressure. Briefly, 980 mL of oil (isopar L)was injected per minute into a stream of water flowing at 2 gpm. Oilvolume was recovered directly from the tube side outflow and the volumeof oil recovered was measured at 5 min intervals.

FIG. 14 is an example of oil/water separation from a ˜12% oil in watermixture with and without a recovery fluid at constant pressure. 1000 mLof oil was injected into a water stream flowing at 2 gpm. Volumes of oilrecovered were determined using a calibrated sight glass when recoveryfluid was used, and by direct measurement of volume recovered from thetube side outflow when recovery fluid was not used. With recovery fluid,the instantaneous recovery is higher in the first minutes of operation.

FIG. 15 is a comparison of pure oil flux rates with and without arecovery fluid. In this study, the test ran at 3 gpm of oil (isopar V)on the shell side with the shell side outlet open. Volumes of oilrecovered were determined using a calibrated sight glass when recoveryfluid was used, and by direct measurement of volume recovered from thetube side outflow when recovery fluid was not used. This experiment alsoshows the approximately linear relationship between pressure and flux,in which the flux rate increases with increasing pressure.

FIG. 16 is an example of oil flux with and without a recovery fluid.This test demonstrates the flux of pure oil (isopar L) as a function ofpressure in the absence of a recovery fluid. For the 10 and 30 psipoints, isopar L was circulated at ˜3 gpm on the shell side of themembrane. Oil volume was recovered directly from the tube side outflow.The test proceeded until 4 L of oil was recovered from the tube side.For the 50 psi dataset, the shell side outflow was capped, forcing theoil to pass through to the tube side. The test proceeded until 4 L ofoil was recovered from the tube side. The average flux rate of duplicateruns is shown.

When considered with the previous figure, this test shows that theviscosity of the oil is a variable in the flux rate. For example, isoparL fluxed at a rate of about 5.5 L per min through the membrane at 30psi. By contrast, the flux rate of isopar V at 30 psi was about 1 L permin in the previous test. The difference in flux rates is directlyrelated to the viscosity of the oils; isopar V (˜17 cSt) issignificantly more viscous than isopar L (˜2 cSt) and fluxes more slowlyat identical operating conditions.

FIG. 17 is an example of oil recovery from wastewater. Approximately 5gallons of oil field wastewater containing light oils and solids ofunknown composition was passed through the contactor to remove the oil.A recovery fluid was not used. The material was circulated through a 2.5inch diameter membrane approximately 10 times with a 30 psi pressuredifferential. At the conclusion of the test, the shell side effluent (A)still contained the solids. A quantity of oil was recovered from thetube side (B).

FIGS. 18A and 18B are examples of water exclusion from oil without arecovery fluid. Approximately 19 liters of isopar L was mixed with 1liter of water and circulated repeatedly through a pump to create anemulsion (FIG. 18A, on left). This mixture was passed through a 4 inchdiameter membrane to exclude the water. The shell side inlet pressurewas 25 psi and a recovery fluid was not used. Oil volume was recovereddirectly from the tube side outflow. The test was stopped once 14 Lisopar L was collected from the tube side outflow (FIG. 18A, on right).Alternately, the water exclusion process can be run with the shell sideoutflow capped; in this case, excluded water accumulates in the shellside of the membrane. FIG. 18B shows a sample of the remaining volumefrom the shell side of the membrane from a similar demonstration; wateris on the bottom and remaining water/oil emulsion is on the top.

It will be understood by the skilled artisan that the process describedhereinabove is applicable broadly for insoluble oil recovery beyondalgae to include protists, fungi, yeast, E. coli, etc., mixed culturesof cells, grown by any method (not limited to photosynthetic organisms),aqueous slurries or aqueous mixtures containing broken and/or live cellsor no cells (in case pre-treated to remove cells/cell debris or othersuspended materials). The process can also be used to recover oil fromany liquid source comprising insoluble oils for e.g. industrial water,brine, wastewater, industrial or natural effluents, water-oil mixtures,aqueous slurries, aqueous slurries comprising broken cells, live cellsor combinations thereof, bio-cellular mixtures, lysed cellularpreparations, and combinations thereof. The process of the presentinvention is capable of recovering almost up to a 100% of the one ormore insoluble oils in the liquid source. The process provides insolubleoil recoveries of 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%,98%, 99% and 100% from the liquid source.

The method and the process of the present invention can be expanded forrecovery of a variety of molecules depending upon choice of recoveryfluid and to include single or multi-step, differential recoveryprocesses for e.g., specifically recover non-polar oil with one membranemodule, then treat the effluent with a second membrane module employinga different recovery fluid. The recovery fluids may be selective,partially selective or non-selective for specific compounds. In otherspecific examples, the present invention may be used to specificallyrecover non-polar oil with one membrane module, then followed bytreatment of the effluent from the first module with a second membranemodule employing a different recovery fluid.

It is contemplated that any embodiment discussed in this specificationcan be implemented with respect to any method, kit, reagent, orcomposition of the invention, and vice versa. Furthermore, compositionsof the invention can be used to achieve methods of the invention.

It will be understood that particular embodiments described herein areshown by way of illustration and not as limitations of the invention.The principal features of this invention can be employed in variousembodiments without departing from the scope of the invention. Thoseskilled in the art will recognize, or be able to ascertain using no morethan routine experimentation, numerous equivalents to the specificprocedures described herein. Such equivalents are considered to bewithin the scope of this invention and are covered by the claims.

All publications and patent applications mentioned in the specificationare indicative of the level of skill of those skilled in the art towhich this invention pertains. All publications and patent applicationsare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

The use of the word “a” or “an” when used in conjunction with the term“comprising” in the claims and/or the specification may mean “one,” butit is also consistent with the meaning of “one or more,” “at least one,”and “one or more than one.” The use of the term “or” in the claims isused to mean “and/or” unless explicitly indicated to refer toalternatives only or the alternatives are mutually exclusive, althoughthe disclosure supports a definition that refers to only alternativesand “and/or.” Throughout this application, the term “about” is used toindicate that a value includes the inherent variation of error for thedevice, the method being employed to determine the value, or thevariation that exists among the study subjects.

As used in this specification and claim(s), the words “comprising” (andany form of comprising, such as “comprise” and “comprises”), “having”(and any form of having, such as “have” and “has”), “including” (and anyform of including, such as “includes” and “include”) or “containing”(and any form of containing, such as “contains” and “contain”) areinclusive or open-ended and do not exclude additional, unrecitedelements or method steps.

The term “or combinations thereof” as used herein refers to allpermutations and combinations of the listed items preceding the term.For example, “A, B, C, or combinations thereof” is intended to includeat least one of: A, B, C, AB, AC, BC, or ABC, and if order is importantin a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB.Continuing with this example, expressly included are combinations thatcontain repeats of one or more item or term, such as BB, AAA, AB, BBC,AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan willunderstand that typically there is no limit on the number of items orterms in any combination, unless otherwise apparent from the context.

All of the compositions and/or methods disclosed and claimed herein canbe made and executed without undue experimentation in light of thepresent disclosure. While the compositions and methods of this inventionhave been described in terms of preferred embodiments, it will beapparent to those of skill in the art that variations may be applied tothe compositions and/or methods and in the steps or in the sequence ofsteps of the method described herein without departing from the concept,spirit and scope of the invention. All such similar substitutes andmodifications apparent to those skilled in the art are deemed to bewithin the spirit, scope and concept of the invention as defined by theappended claims.

REFERENCES

-   U.S. Pat. No. 4,439,629: Extraction Process for Beta-Carotene.-   U.S. Pat. No. 5,378,639: Solvent Extraction.

What is claimed is:
 1. A method of recovering one or more insoluble oilsfrom an aqueous mixture using one or more membrane contactors,comprising the steps of: pumping, from a growth environment, the aqueousmixture comprising the one or more insoluble oils into contact with afirst surface of the one or more membrane contactors, wherein theaqueous mixture does not contain an amount of solvent sufficient todisperse the insoluble oils, and wherein the aqueous mixture comprisesone or more organisms that include at least one of intact cells, lysedcells, apoptotic cells, necrotic cells, wherein the aqueous mixturecomprises two or more different organisms, wherein the aqueous mixturecomprises a yeast, algae or bacteria, or wherein the aqueous mixturecomprises organisms capable of secreting oil or causing accumulation ofoil outside living cells; coalescing the one or more insoluble oils fromthe aqueous mixture onto the first surface of the one or more membranecontactors, wherein the one or more membrane contactors are filed with arecovery fluid coalescing the one or more insoluble oils; collecting astream of coalesced insoluble oil from a second surface of the one ormore membrane contactors, wherein the stream comprises coalescedinsoluble oil and the recovery fluid; and returning the aqueous mixtureto the growth environment after the one or more insoluble oils areseparated from the aqueous mixture.
 2. The method of claim 1, whereinthe aqueous mixture is subjected to the pumping within 1, 2, 4, 6, 8,12, 24, 26, 48 or 72 hours from production.
 3. The method of claim 1,wherein the aqueous mixture comprises one or more organisms that aregenetically modified to render them capable of secreting hydrophobiccomponents, one or more organisms that are capable of causingaccumulation of the hydrophobic components outside living cells, or oneor more organisms that are capable of causing accumulation of thehydrophobic components outside living cells upon induction with one ormore chemical probes, exogenous agents, or pharmaceuticals, orcombinations thereof.
 4. The method of claim 1, further comprising:contacting the one or more organisms with chemical probes, exogenousagents, or pharmaceuticals, whereby a metabolism of the one or moreorganisms is modified, and wherein at least one organism causesaccumulation of the one or more insoluble oils outside living cells. 5.The method of claim 1, wherein 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%,85%, 90%, 95%, 98%, 99% or 100% of the one or more insoluble oils in theaqueous mixture are recovered.
 6. The method of claim 1, whereinreturning the aqueous mixture to the growth environment includesreturning the one or more organisms to the growth environment to for oilproduction.
 7. The method of claim 1, wherein the one or more membranecontactors comprise a material selected from at least one ofpolyethylene, polypropylene, polyolefins, polyvinyl chloride (PVC),amorphous Polyethylene terephthalate (PET), polyolefin copolymers,poly(etheretherketone) type polymers, surface modified polymers, orsurface modified polymers comprising polymers modified chemically at oneor more halogen groups by corona discharge or by ion embeddingtechniques.
 8. The method of claim 1, wherein the stream comprising thecoalesced insoluble oil and the recovery fluid is not counterflowing. 9.The method of claim 1, wherein the recovery fluid comprises previouslycoalesced insoluble oil.
 10. A method of recovering one or moreinsoluble oils from an aqueous mixture using one or more membranecontactors, comprising the steps of: pumping the aqueous mixturecomprising the one or more insoluble oils into contact with a firstsurface of the one or more membrane contactors, wherein the aqueousmixture does not contain an amount of solvent sufficient to disperse theinsoluble oils and wherein the aqueous mixture comprises one or moreorganisms that include at least one of intact cells, lysed cells,apoptotic cells, necrotic cells, or wherein the aqueous mixturecomprises two or more different organisms, wherein at least one of theorganisms produces oil, or wherein the aqueous mixture comprises ayeast, algae or bacteria, or wherein the aqueous mixture comprisesorganisms capable of secreting oil or causing accumulation of oiloutside living cells, or wherein the aqueous mixture comprises one ormore organisms that are genetically modified to render them capable ofsecreting hydrophobic components, or wherein the aqueous mixturecomprises one or more organisms that are capable of causing accumulationof the hydrophobic components outside living cells, or wherein theaqueous mixture comprises one or more organisms that are capable ofcausing accumulation of hydrophobic components outside living cells uponinduction with one or more chemical probes, exogenous agents, orpharmaceuticals, or combinations thereof; coalescing the one or moreinsoluble oils from the aqueous mixture onto the first surface of theone or more membrane contactors, wherein the one or more membranecontactors are filled with a recovery fluid coalescing the oils; andcollecting a stream of coalesced insoluble oil from a second surface ofthe one or more membrane contactors, wherein the stream comprisescoalesced insoluble oil and the recovery fluid.
 11. The method of claim10, further comprising: contacting the one or more organisms withchemical probes, exogenous agents, or pharmaceuticals, whereby ametabolism of the one or more organisms is modified, and wherein atleast one organism causes accumulation of the one or more insoluble oilsoutside living cells.
 12. The method of claim 10, wherein the streamcomprising the coalesced insoluble oil and the recovery fluid is notcounterflowing.
 13. The method of claim 10, wherein the recovery fluidcomprises previously coalesced insoluble oil.
 14. A method of recoveringone or more insoluble oils from an aqueous mixture using one or moremembrane contactors, comprising the steps of: pumping the aqueousmixture comprising the one or more insoluble oils from a growthenvironment for organisms including algae, bacteria or yeast, whereinthe aqueous mixture does not contain an amount of solvent sufficient todisperse the insoluble oils; contacting a first surface of the one ormore membrane contactors with the aqueous mixture, wherein the aqueousmixture comprises a growth media and the one or more insoluble oilsproduced by the growth environment; coalescing the one or more insolubleoils from the aqueous mixture onto the first surface of the one or moremembranes or membrane contactors, wherein the one or more membranecontactors are filled with a recovery fluid coalescing the one or moreinsoluble oils; removing a first stream from the one or more membranecontactors, wherein the first stream comprises the growth media andorganisms, wherein the organisms can continue to produce the one or moreinsoluble oils; and removing a second stream from a second surface ofone or more membrane contactors, wherein the second stream comprises theone or more insoluble oils and the recovery fluid.
 15. The method ofclaim 14, further comprising feeding or pumping the first stream to thegrowth environment to for oil production by the organisms.
 16. Themethod of claim 14, wherein the one or more membrane contactors comprisea material selected from at least one of polyethylene, polypropylene,polyolefins, polyvinyl chloride (PVC), amorphous Polyethyleneterephthalate (PET), polyolefin copolymers, poly(etheretherketone) typepolymers, surface modified polymers, or surface modified polymerscomprising polymers modified chemically at one or more halogen groups bycorona discharge or by ion embedding techniques.
 17. The method of claim14, wherein the second stream comprising the one or more insoluble oilsand the recovery fluid is not counterflowing.
 18. The method of claim14, wherein the recovery fluid comprises previously coalesced insolubleoil.